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4dc35c6810
including third-body and pressure dependent derivatives, and derivative of the
temperature term. The complete Jacobian is more robust than the incomplete and
partially approximate form used previously and improves the efficiency of the
stiff ODE solvers which rely on the Jacobian.
Reaction rate evaluation moved from the chemistryModel to specie library to
simplfy support for alternative reaction rate expressions and associated
Jacobian terms.
Temperature clipping included in the Reaction class. This is inactive by default
but for most cases it is advised to provide temperature limits (high and
low). These are provided in the foamChemistryFile with the keywords Thigh and
Tlow. When using chemkinToFoam these values are set to the limits of the Janaf
thermodynamic data. With the new Jacobian this temperature clipping has proved
very beneficial for stability and for some cases essential.
Improvement of the TDAC MRU list better integrated in add and grow functions.
To get the most out of this significant development it is important to re-tune
the ODE integration tolerances, in particular the absTol in the odeCoeffs
sub-dictionary of the chemistryProperties dictionary:
odeCoeffs
{
solver seulex;
absTol 1e-12;
relTol 0.01;
}
Typically absTol can now be set to 1e-8 and relTol to 0.1 except for ignition
time problems, and with theses settings the integration is still robust but for
many cases a lot faster than previously.
Code development and integration undertaken by
Francesco Contino
Henry G. Weller, CFD Direct
92 lines
2.2 KiB
C
92 lines
2.2 KiB
C
/*---------------------------------------------------------------------------*\
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========= |
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\\ / F ield | OpenFOAM: The Open Source CFD Toolbox
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\\ / O peration |
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\\ / A nd | Copyright (C) 2011-2018 OpenFOAM Foundation
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\\/ M anipulation |
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-------------------------------------------------------------------------------
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License
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This file is part of OpenFOAM.
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OpenFOAM is free software: you can redistribute it and/or modify it
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under the terms of the GNU General Public License as published by
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the Free Software Foundation, either version 3 of the License, or
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(at your option) any later version.
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OpenFOAM is distributed in the hope that it will be useful, but WITHOUT
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ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
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FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License
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for more details.
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You should have received a copy of the GNU General Public License
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along with OpenFOAM. If not, see <http://www.gnu.org/licenses/>.
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\*---------------------------------------------------------------------------*/
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// * * * * * * * * * * * * * * * * Constructors * * * * * * * * * * * * * * //
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inline Foam::LindemannFallOffFunction::LindemannFallOffFunction()
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{}
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inline Foam::LindemannFallOffFunction::LindemannFallOffFunction
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(
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const dictionary& dict
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)
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{}
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// * * * * * * * * * * * * * * * Member Functions * * * * * * * * * * * * * //
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inline Foam::scalar Foam::LindemannFallOffFunction::operator()
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(
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const scalar,
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const scalar
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) const
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{
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return 1.0;
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}
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inline Foam::scalar Foam::LindemannFallOffFunction::ddT
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(
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const scalar,
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const scalar,
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const scalar,
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const scalar
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) const
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{
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return 0;
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}
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inline Foam::scalar Foam::LindemannFallOffFunction::ddc
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(
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const scalar,
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const scalar,
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const scalar,
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const scalar
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) const
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{
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return 0;
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}
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inline void Foam::LindemannFallOffFunction::write(Ostream& os) const
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{}
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// * * * * * * * * * * * * * * * Ostream Operator * * * * * * * * * * * * * //
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inline Foam::Ostream& Foam::operator<<
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(
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Foam::Ostream& os,
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const Foam::LindemannFallOffFunction&
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)
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{
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return os;
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}
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// ************************************************************************* //
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